This format is designed to render 2 pages on an A4 paper. The printed version will be fliped at the center and the result will be a nice book format.
For the best results on a regular printer follow this steps:
Note: On some computers and printers an extra marging may be added or the content itself may be rescaled. So please check you have the right configurations. You can try print only 1,2 pages and see if everything is printed fine and the fliping step will not cover the text.
The PDF will look like this. Don't worry it's not an error or bug, all the messed up pages. Just try print the curent lesson, and see how it works. If you encounter any problem, contact me.